This invention relates to power tools, and more particularly, to improved scroll saws or jig saws wherein a saw blade is connected between the free ends of a pair of arm members, which are oscillated in unison about their respective pivot points at high speed.
Such rapid reciprocation of the arm members creates large inertial forces, which can result in severe vibration of the entire saw assembly unless it is bolted or otherwise secured by a large mass. To offset these inertial forces, it is known to provide a counterbalancing assembly mounted in a separate housing which is bolted or otherwise attached to a portion of the saw, such as its base. Additionally, the saw blade must be accurately positioned and placed under the correct amount of tension for successful operation. Many prior art devices include relatively complicated blade mounting and tensioning mechanisms, rendering accurate positioning and tensioning of the blade a tedious and difficult procedure.
In order to remove saw dust and other debris resulting from the sawing operation, it is conventional to provide a system for delivering an air stream to the cutting area. Furthermore, in order to protect the user from accidental contact with the blade, a saw is usually provided with some sort of guard. However, where provision is made in prior art devices for removal of saw dust and the like and/or a guard against inadvertent contact with the blade, separate saw guards and airblast assemblies are utilized, thereby increasing the cost and the complexity of the saw.
It will be apparent, therefore, that despite long-standing use of scroll saws, it is conventional to utilize separate gear and counterweight casings, blade positioning and tensioning mechanisms that are both tedious and difficult to adjust properly and, where provided at all, separate systems for removing saw dust and other debris from the cutting area and guarding against inadvertent contact with the saw blade.